Vaginal devices for delivering one or more pharmaceutical actives are known.
For example, U.S. Pat. Nos. 3,995,633 and 3,995,634, describe separate, preferably spherical or cylindrical, reservoirs containing different active substances which are assembled in specially constructed holders. U.S. Pat. No. 4,237,885 describes a tube or coil of polymeric material which is divided into portions by means of a plurality of “spacers” provided in the tube, after which each of the separate tube portions is filled with a different active substance in a silicone fluid and the two ends of the tube are subsequently connected to one another. In this release system, however, transport (diffusion) of active material from one reservoir to the other takes place through the wall of the tube, especially upon prolonged storage, so that the pre-set fixed release ratio between the active substances in question will change over a period of time.
EP 0 050 867 discloses a two-layered vaginal ring which comprises a pharmacologically acceptable supporting ring covered by two layers preferably of silicone elastomers whereby the inner layer is a silicone elastomer loaded with an active substance.
U.S. Pat. No. 4,292,965 describes a ring shaped vaginal delivery system of three layers made of silicone elastomers. This patent describes in the background section different types of known intravaginal rings, and then claims to have developed an improved shell-type intravaginal ring of the type shown in FIG. 4 of the '965 patent. The layered device shown in this patent is specifically produced by methods which are described beginning at column 6, line 20 of the '965 patent. In each of these procedures, separate elastomeric rings, whether they include organopolysiloxanes or the like, are cured prior to joining with additional such layers. Thus, for example, in each case an annular core ring is cured prior to various procedures such as expansion by exposure to organic solvents to assist in layering with a further cured layer and the like. In each case, this thus leads to separate cured layers which create distinct physical junctions in the ring impeding drug diffusion through the intravaginal ring itself.
U.S. Pat. No. 4,596,576 describes a two-compartment vaginal ring wherein each compartment contains a different active substance. To achieve a suitable ring with a constant release ratio between the various active substances, the end portions of the compartments are joined by glass stoppers.
Patent Publication WO 97/02015 describes a two-compartments device, a first compartment consisting of a core, a medicated middle layer and a non medicated outer layer, and a second compartment consisting of a medicated core and a non medicated outer layer.
EP 876 815 discloses a vaginal ring which is designed for the simultaneous release of a progestogenic steroid compound and an estrogenic steroid compound in a fixed physiological ratio over a prolonged period of time. The drug delivery system comprises one compartment comprising a thermoplastic polymer core containing the mixture of the progestogenic and estrogenic compounds and a thermoplastic polymer skin, the progestogenic compound being initially dissolved in the polymer core material in a relatively low degree of supersaturation.
From the above disclosures, it is clear that e.g., the material, the layers and the compartments are all aspects of a ring device which play a role in the designs that have been developed.